Differences in single gland and multigland disease are seen in low biochemical profile primary hyperparathyroidism

Normocalcemic primary hyperparathyroidism: From pathophysiology to clinical management

Normocalcemic primary hyperparathyroidism (NPHPT), a variant of primary hyperparathyroidism (PHPT) characterized by persistently elevated parathyroid hormone (PTH) levels and normal serum calcium, has gained recognition as a substantial subset of PHPT cases. Despite its increasing prevalence, the precise pathophysiology and natural progression of NPHPT remain enigmatic. This in-depth literature review explores recent advancements in our understanding of NPHPT, encompassing pathophysiology, clinical presentation, diagnostic approaches, medical and surgical management options. By synthesizing this wealth of information, this review aims to contribute to a more nuanced and informed approach to the treatment of patients grappling with NPHPT. As our understanding of the condition continues to evolve, the knowledge gathered from this review has the potential to significantly enhance the quality of care and outcomes for individuals afflicted with NPHPT, ultimately improving their overall well-being and prognosis.

Bilateral exploration in primary hyperparathyroidism: Double adenoma distribution and biochemical patterns over two decades

BACKGROUND

We investigated if anatomic patterns of abnormal parathyroid glands have ch anged for primary hyperparathyroidism (pHPT) as atypical biochemical presentation (normohormonal and normocalcemic) has increased.

METHODS

Retrospective review of patients with pHPT who underwent routine bilateral neck exploration.

RESULTS

2762 patients were included. The "late" cohort (2014-2020) exhibited lower preoperative calcium (10.8 vs 11.1 ​mg/dL; P ​= ​0.001) and PTH levels (101 vs. 146 ​pg/mL; P ​= ​0.001) compared to the "early" cohort (2000-2006). Patients with atypical biochemical profiles increased from 25.5% to 31.3% (P ​< ​0.001). The prevalence of single adenoma (SA) decreased (66.1% vs 58.9%, P ​= ​0.02) while the proportion of double adenoma (DA) increased (17.3% vs. 22.6%, P ​< ​0.01). Upper parathyroid adenoma(s) remained the most common finding for SA and DA in both time points.

CONCLUSIONS

Despite changes in patient characteristics, single upper adenoma and bilateral double upper adenomas remain the most common findings for patients with pHPT.

Intraoperative Parathyroid Hormone Monitoring In Normohormonal Primary Hyperparathyroidism: How Low Do You Go?

OBJECTIVE

The primary goal of this study was to determine in patients with normohormonal primary hyperparathyroidism (NHHPT) what percent reduction in post-excision intraoperative parathyroid hormone (IOPTH) from baseline would yield a rate of cure comparable to that in patients with classical primary hyperparathyroidism (PHPT).

METHODS

This is a retrospective cohort study of patients who underwent parathyroidectomy between July 2013 and February 2020. Demographic data, preoperative, intraoperative, and postoperative metrics were collected. Patients with NHHPT were compared to those with classical PHPT. Subgroup analyses were performed.

RESULTS

Of the 496 patients included in the study, 66 (13.3%) were of the normohormonal variant based on preoperative intact parathyroid hormone (PTH) levels and 28 (5.6%) based on baseline IOPTH levels. The cure rates in the two normohormonal groups were not significantly different from their classical counterparts (98.4% and 100.0% vs. 97.1%, p = 1.000). The median percent decline in post-excision IOPTH from baseline that achieved cure in the normohormonal groups were 82.6% and 80.4% compared to their respective controls at 87.3%, p = 0.011 and p = 0.001. Although the rate of multiglandular disease was higher in one of the normohormonal variant groups, this difference was due to a higher rate of double adenomas, not four-gland hyperplasia.

CONCLUSION

Patients with NHHPT undergoing parathyroidectomy can expect cure rates similar to that in patients with classical PHPT. The results of this study indicate that achieving an 80% drop or more in IOPTH levels predicts a high likelihood of cure. This is true irrespective of whether the patient is deemed normohormonal based on preoperative or intraoperative testing.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:2480-2484, 2024.

Normohormonal primary hyperparathyroidism: A systematic review and meta-analysis

OBJECTIVE

We aim to evaluate the body of evidence reporting on normohormonal primary hyperparathyroidism (NHpHPT) patients to help guide their diagnosis, characterization and treatment.

BACKGROUND

Normohormonal primary hyperparathyroidism is a term used to describe patients with a normal PTH and elevated calcium levels. There is limited understanding regarding the presentation and appropriate management of these patients.

METHODS

A systematic review was conducted: abstract and full-text screening were independently conducted by 2 investigators. Odds ratios (OR), standard mean differences (SMD) and 95% confidence intervals were calculated.

RESULTS

Twenty-two studies were identified. Patients with NHpHPT were more likely to present with lower PTH (p < 0.00001) and calcium (p < 0.00001) levels. Intraoperatively, the NHpHPT group was 1.8 times more likely to undergo bilateral neck exploration (BNE) and harbor multigland disease. The rates of surgical cure were 93% in the NHpHPT and 96% in the pHPT groups (p = 0.0003).

CONCLUSION

Symptomatic patients with NHpHPT benefit from parathyroidectomy with prolonged intraoperative PTH monitoring, and a low threshold for conversion to BNE.

FCH-PET/CT in Primary Hyperparathyroidism With Discordant/Negative MIBI Scintigraphy and Ultrasonography

CONTEXT

The contribution of [18F]F-fluorocholine (FCH)-positron emission tomography (PET)/computed tomography (CT) in normocalcemic primary hyperparathyroidism (nPHPT) remains unknown.

OBJECTIVE

To evaluate the sensitivity and specificity of FCH-PET/CT in a cohort of osteoporotic patients with nPHPT and discordant or negative [99mTc]Tc-sestamibi scintigraphy and ultrasonography who all underwent parathyroidectomy (PTX).

DESIGN

Longitudinal retrospective cohort study in patients referred for osteoporosis with mild biological primary hyperparathyroidism.

SETTING

Tertiary referral center with expertise in bone metabolism and surgical management of hyperparathyroidism.

PATIENTS

Among 109 patients with PHPT analyzed, 3 groups were individualized according to total serum calcium (tCa) and ionized calcium (iCa): 32 patients with hypercalcemia (HtCa group), 39 patients with normal tCa and elevated iCa (NtCa group), and 38 patients with both normal tCa and iCa (NiCa). All patients had biochemical follow-up confirming or not the success of PTX.

MAIN OUTCOME MEASURES

To evaluate the performance of FCH-PET/CT in terms of sensitivity and specificity, and to compare with first-line imaging procedures in the setting of nPHPT.

RESULTS

The sensitivity of FCH-PET/CT was 67% in the hypercalcemic group, 48% in the NtCa group (P = .05 vs HtCa), and 33% in the NiCa group (P = .004 vs HtCa). Specificity ranged from 97% to 99%. FCH-PET/CT was positive in 64.3% of patients with negative conventional imaging, with biochemical resolution after PTX in 77.8% of patients. Triple negative imaging was observed in 20 patients, with PHPT resolution in 85% of these patients.

CONCLUSION

This study highlights the contribution of FCH-PET/CT in a well-phenotyped cohort of normocalcemic patients with discordant or negative findings in [99mTc]Tc-sestamibi scintigraphy and ultrasonography. However, negative imaging in nPHPT does not rule out the possibility of surgical cure by an experienced surgeon.

The Eucalcemic Patient With Elevated Parathyroid Hormone Levels

Primary hyperparathyroidism (PHPT) is classically characterized by hypercalcemia with elevated or inappropriately normal parathyroid hormone (PTH) levels. Elevated PTH levels in the presence of normal calcium levels are not infrequently found during the evaluation of metabolic bone disorders or kidney stone disease. This can be caused by secondary hyperparathyroidism (SHPT) or normocalcemic primary hyperparathyroidism (NPHPT). NPHPT is due to autonomous parathyroid function whereas SHPT is caused by a physiologic stimulation to PTH secretion. Many medical conditions and medications can contribute to SHPT, and differentiation between SHPT and NPHPT may be difficult. Cases are presented to illustrate examples. In this paper, we review the distinction between SHPT and NPHPT as well as end organ effects of NPHPT and outcomes of surgery in NPHPT. We suggest that the diagnosis of NPHPT be made only after careful exclusion of causes of SHPT and consideration of medications that can increase PTH secretion. Further, we advise a conservative approach to surgery in NPHPT.

Normocalcaemic primary hyperparathyroidism: is nephrolithiasis more common than osteoporosis?

BACKGROUND

Normocalcaemic primary hyperparathyroidism (NPHPT) is often under-recognised in clinical practice.

AIM

To determine the prevalence and clinical significance of NPHPT in an unselected sample in an acute hospital setting.

METHODS

Patients aged >18 years who had measurement of an elevated serum parathyroid hormone (PTH ≥ 7 pmol/L) during 12 months from 1 January 2017 to 31 December 2017 were retrospectively studied. NPHPT was defined by the presence of elevated serum PTH with normal albumin-corrected serum calcium on two or more occasions after excluding secondary causes. Patients were followed up for 2 years. Relevant data were collected by review of electronic medical records.

RESULTS

Of the 2593 patients who had PTH measured during the study period, 1278 had serum PTH ≥ 7 pmol/L. Hypercalcaemic primary hyperparathyroidism (PHPT) was diagnosed in 174 patients. Secondary causes for elevated serum PTH were identified in 993 patients: 815 (chronic kidney disease - estimated glomerular filtration rate < 60 mL/min/1.73 m² or renal transplant), 98 (vitamin D deficiency - 25(OH)D < 50 nmol/L), 28 (gastric bypass surgery), 38 (medications), 13 (malabsorption or post-thyroidectomy) and 1 (hypercalciuria). Data were incomplete for 80 patients. The prevalence of NPHPT with and without the exclusion of hypercalciuria was 0.19% (5) and 0.39% (10) respectively. The prevalence of nephrolithiasis in NPHPT was higher than PHPT (100% vs 15% among five patients (P < 0.001) and 50% vs 15% among 10 patients (P = 0.014)). The prevalence of osteoporosis was not significantly different between NPHPT and PHPT (20% vs 45% among five patients (P = 0.389) and 30% vs 45% among 10 patients (P = 0.518)).

CONCLUSION

These findings give further credence to the diagnosis of NPHPT as a clinical entity. Nephrolithiasis may be a greater problem than osteoporosis in NPHPT compared with PHPT. This needs prospective evaluation.

Phenotypes of primary hyperparathyroidism: Does parathyroidectomy improve clinical outcomes for all?

BACKGROUND

Primary hyperparathyroidism consists of 3 biochemical phenotypes: classic, normocalcemic, and normohormonal primary hyperparathyroidism. The clinical outcomes of patients with normocalcemic primary hyperparathyroidism and normohormonal primary hyperparathyroidism are not well described.

METHOD

A retrospective review of patients who underwent parathyroidectomy at a single institution was performed. A logistical regression analysis of postoperative nephrolithiasis and highest percentage change in dual-energy x-ray absorptiometry scan comparison using Kruskal-Wallis test and Cox proportional hazard analysis of recurrence-free survival were performed.

RESULTS

A total of 421 patients were included (340 classic, 39 normocalcemic primary hyperparathyroidism, 42 normohormonal primary hyperparathyroidism). Median follow-up was 8.8 months (range 0-126). Higher rates of multigland disease were seen in normocalcemic primary hyperparathyroidism (64.1%) and normohormonal primary hyperparathyroidism (56.1%) compared to the classic (25.8%), P < .001. There were no differences in postoperative complications. The largest percentage increases in bone mineral density at the first postoperative dual-energy x-ray absorptiometry scan were higher for classic (mean ± SD, 6.4 ± 9.1) and normocalcemic primary hyperparathyroidism (4.8 ± 11.9) compared to normohormonal primary hyperparathyroidism, which remained stable (0.2 ± 14.2). Normocalcemic primary hyperparathyroidism were more likely to experience nephrolithiasis postoperatively, 6/13 (46.2%) compared to 11/68 (16.2%) classic, and 2/13 (15.4%) normohormonal primary hyperparathyroidism, P = .0429. Normocalcemic primary hyperparathyroidism was the only univariate predictor of postoperative nephrolithiasis recurrence (odds ratio [95% confidence interval] 4.44 [1.25-15.77], P = .029). Normocalcemic primary hyperparathyroidism was significantly associated with persistent disease with 6/32 (18.8%) compared to 1/36 (2.8%) and 3/252 (1.2%) in normohormonal primary hyperparathyroidism and classic (P < .001).

CONCLUSION

Three phenotypes of primary hyperparathyroidism are distinct clinical entities. Normocalcemic primary hyperparathyroidism had higher incidence of persistent disease and postoperative nephrolithiasis but demonstrated improvements in postoperative bone density. These data should inform preoperative discussions with patients with normocalcemic primary hyperparathyroidism and normohormonal primary hyperparathyroidism regarding postoperative expectations.

Surgery for primary hyperparathyroidism

Primary hyperparathyroidism (PHPT) is a hypercalcemic disorder that occurs when one or more parathyroid glands produces excessive parathyroid hormone (PTH). PHPT is typically treated with surgery, and it remains the only definitive therapy, whose techniques have evolved over previous decades. Advances in preoperative localization exams and the intraoperative PTH monitoring have become the cornerstones of recent parathyroidectomy techniques, as minimally invasive techniques are appropriate for most patients. Nevertheless, these techniques, are not suitable for PHPT patients who are at risk for multiglandular disease, especially in those who present with familial forms of PHPT that require bilateral neck exploration. This manuscript also explores other conditions that warrant special consideration during surgical treatment for PHPT: normocalcemic primary hyperparathyroidism, pregnancy, reoperation for persistent or recurrent PHPT, parathyroid carcinoma, and familial and genetic forms of hyperparathyroidism.

Comparisons Between Normocalcemic Primary Hyperparathyroidism and Typical Primary Hyperparathyroidism

BACKGROUND

Normocalcemic primary hyperparathyroidism (NPHPT) was first described in 2008. It is defined as consistently elevated serum parathyroid hormone (PTH) levels with normal serum calcium (sCa) concentration, after excluding secondary causes of PTH elevation. However, the exact definition and management strategy for NPHPT remain controversial. We retrospectively investigated the clinicopathological features and short-term outcomes of NPHPT patients.

METHODS

A total of 280 patients who were surgically indicated for primary hyperparathyroidism (PHPT) at the Yonsei Severance Medical Center between 2015 and 2019 were included. Patients were classified according to preoperative PTH, corrected sCa, and ionized calcium (iCa) levels as follows: typical primary hyperparathyroidism (TPHPT, elevated PTH, sCa, and iCa, n = 158) and NPHPT (elevated PTH, normal sCa, n = 122).

RESULTS

NPHPT was commonly seen in younger individuals (aged < 50 years, P = 0.025); nephrolithiasis and bone fractures were common. Preoperative PTH level was higher in the TPHPT group (P < 0.001). The NPHPT group had higher numbers of multiple parathyroid lesions (P = 0.004) that were smaller (P = 0.011). NPHPT patients were further divided into two subgroups according to iCa levels: the elevated (n = 95) and normal iCa (n = 27) groups. There was no significant difference between the two subgroups regarding symptoms and multiplicity of lesions.

CONCLUSION

We found that NPHPT may be a heterogeneous disease entity of PHPT with high rates of multi-gland disease, which appears to be biochemically milder but symptomatic. Intraoperative PTH monitoring might help increase the surgery success rate. Moreover, the short-term outcomes of NPHPT after surgery did not differ from that of TPHPT.

Evaluation and Management of Elevated Parathyroid Hormone Levels in Normocalcemic Patients

Primary hyperparathyroidism is a common endocrine disorder. It used to present as a highly symptomatic disease before the advent of the multichannel autoanalyzer, now usually presenting as mild asymptomatic hypercalcemia. A newer presentation has been increasingly identified in the past two decades, normocalcemic primary hyperparathyroidism, presenting with elevated parathyroid hormone concentrations and consistently normal serum calcium. These patients are usually symptomatic, with parathyroid hormone levels measured in the evaluation for kidney stones or osteoporosis. It is important to exclude causes of secondary hyperparathyroidism. This review will focus on the evaluation and management of elevated parathyroid hormone levels in normocalcemic patients.

A practical approach to normocalcemic primary hyperparathyroidism

Normocalcemic primary hyperparathyroidism is an entity on which several issues about its clinical management remains unclear. This is reflected in the main current guidelines, where there are no evidence-based specific recommendations. Through an exhaustive review of current literature, a clinical management algorithm for these patients is proposed. We consider the diagnosis criteria, the differential diagnosis, the clinical manifestations, and the treatment indications. When indicated, we also review the preoperative locations techniques and the surgical approach. Finally, when surgical treatment is not indicated, the patient is not a candidate to surgery or refuse surgical management, we review the medical treatment options and the follow-up schemes.

Surgical management of MILD hyperparathyroidism

INTRODUCTION

There is no consensus for management of Mild primary hyperparathyroidism (MILD-pHP). Specific management has been suggested by some authors. We have compared the surgical management of the patients with MILD-pHP to those with Classic primary hyperparathyroidism (C-pHP) treated by surgery according to The Fourth International Workshop on pHP.

MATERIALS AND METHODS

Data of 173 patients who underwent a parathyroidectomy were reviewed and retrospectively analysed. Management of 32 patients with MILD-pHPT (18.5%) patients were compared to that of 141 (81.5%) patients with C-pHPT.

RESULTS

MILD-pHP group was more often discovered after non-fractured osteoporosis (21.9% vs 7.1%, p = 0.02) and surgery for chondrocalcinosis was more often carried out (6.3% vs 0%, p = 0.03) in the MILD-pHP group. A Mini-Invasive Parathyroidectomy (MIP) was carried out in 81.3% of cases, and 87.5% of patients had a single adenoma. The rate of multiglandular pathology was not different. Same day discharge was significantly higher in MILD-pHP group (37.5% vs 17.7%, p = 0.01). Success was obtained in 87.5% in the MILD-pHP group, there was no significant difference with the C-pHP group (92.9%, p = 0.48). There was no significant difference in the imaging performances. Imaging discordance was observed in 18.8% of cases in MILD-pHP and 33.6% in C-pHP (p = 0.38) without correlation with surgical failure.

CONCLUSION

This study suggests that, by selecting patients on the basis of concordant imaging and international recommendations, there is no difference in outcome between MILD-pHP and C-pHP treated surgically.

Bones and Primary Hyperparathyroidism

Primary hyperparathyroidism (PHPT) is a disease caused by excessive and inappropriate secretion of parathyroid hormone resulting in hypercalcemia. It is usually diagnosed incidentally in the face of hypercalcemia, a complication such as osteoporosis or, more rarely, a renal complication with lithiasis. The clinical presentation reflects hypercalcemia and involves several organs, mainly the cardiovascular system, bones, and kidneys. However, most patients with PHPT are asymptomatic. The diagnosis is made based on laboratory tests. It is easy when serum calcium and parathyroid hormone levels are high, but difficult when one of these two values is normal. Normocalcemic PHPT can be diagnosed only after ruling out all causes of secondary hyperparathyroidism. Parathyroid imaging cannot diagnose it but guides the surgeon and rules out an associated thyroid abnormality. The reference treatment is surgery. The surgical indication is based on the presence or risk of complications, and it is the only treatment that prevents fractures. Pharmaceutical treatments have only limited effects on complications and are reserved for cases where surgery is contraindicated. After parathyroid surgery, the use of bisphosphonates must be avoided as they seem to interfere with the parathyroidectomy's fracture-preventing effects. If surgery is not indicated, a plan for monitoring laboratory values, bone density, and renal function will be established.

Normocalcemic and Normohormonal Primary Hyperparathyroidism: Laboratory Values and End-Organ Effects

OBJECTIVE

Variants of primary hyperparathyroidism (pHPT), described as normocalcemic (NC) and normohormonal (NH), can confuse the diagnosis of classic pHPT.

DATA SOURCES

A MEDLINE search was performed for variants of pHPT using the PubMed database (last queried October 2019).

REVIEW METHODS

The search was restricted to articles published after 1960 that were specific to humans. Studies were included in our analysis if laboratory values and incidence of end-organ involvement were reported for NCpHPT and NHpHPT variants. The search returned 189 articles; 27 additional studies were identified and included for a total of 216. Non-English-language studies were excluded. Abstracts were screened, full-text articles were then assessed, and 82 articles were excluded. Data were pooled using a random-effects model in studies that compared NC or NH pHPT to classic pHPT. Comparative laboratory values are presented.

CONCLUSION

This analysis compares NCpHPT and NHpHPT to classic pHPT. Nephrolithiasis was 21.7% (NCpHPT), 15.9% (classic pHPT), and 25.4% (NHpHPT). Decreased bone mineral density was 49.7% (NCpHPT), 39.7% (classic pHPT), and 40.3% (NHpHPT). Fractures in the NCpHPT group were not significantly different from the classic pHPT. Hypertension in the NCpHPT group was significantly less than classic pHPT (odds ratio, 0.59; 95% CI, 0.40-0.88).

IMPLICATIONS FOR CLINICAL PRACTICE

This information may serve to inform clinicians of the laboratory subtleties of these variants that are being seen with greater frequency in contemporary practice.

Normocalcaemic primary hyperparathyroidism: what is the role of parathyroid surgery?

Primary hyperparathyroidism (PHPT) is classically associated with both an elevated or 'inappropriately normal' parathyroid hormone (PTH) level and raised serum calcium. However, in clinical practice, increasing numbers of patients present with raised PTH but normal serum calcium, renal function and vitamin D; this is known as normocalcaemic PHPT (nPHPT). Studies investigating the clinical presentation of this condition have shown that patients may present with hypertension, nephrolithiasis, impaired glucose tolerance, osteoporosis and fragility fractures. The prevalence of such complications in nPHPT is similar to that in classical hypercalcaemic PHPT (hPHPT). Although the National Institute for Health and Care Excellence (NICE) have developed guidelines for the management of PHPT generally, a consensus is yet to be reached on the optimal management of nPHPT specifically. A review of the literature on parathyroidectomy in the treatment of nPHPT revealed that nPHPT patients were more likely to present with multi-glandular disease and significantly less nPHPT patients had an intra-operative PTH fall of >50% compared with those with hPHPT. These findings demonstrate that patients with nPHPT are more likely to receive bilateral neck explorations and require remedial surgery compared with hPHPT patients. Following surgery, improvements in bone mineral density (BMD) and renal stones are generally observed in those with nPHPT. Where surgery is not possible, medical management with alendronate has been shown to be effective in nPHPT patients. Given the higher incidence of multi-gland disease and greater possibility of remedial surgery in nPHPT, careful consideration of risks and benefits should be made on an individualised basis and surgery should be performed by surgeons experienced in four gland exploration.

Biochemical Profile Affects IOPTH Kinetics and Cure Rate in Primary Hyperparathyroidism

BACKGROUND

Recently, normocalcemic (NC) and normohormonal (NH) variants of primary hyperparathyroidism (pHPT) have been described, with distinct biochemical profiles from the typical high serum calcium and parathyroid hormone (PTH) levels. Here, we investigate whether biochemical profile affects cure rate, as well as the kinetics of intraoperative PTH (IOPTH).

METHODS

This is a single-center, retrospective study of pHPT patients undergoing parathyroidectomy. Patients were grouped based on preoperative calcium and PTH levels into typical, NC (normal calcium, elevated PTH, no evidence of secondary hyperparathyroidism), and NH (elevated calcium, unsuppressed PTH) biochemical profiles. All patients had IOPTH monitoring and ≥6-month post-op serum studies to confirm surgical cure. Patient variables were analyzed with Kruskal-Wallis test and Chi-square analysis. IOPTH kinetic curves were analyzed using a linear mixed model.

RESULTS

From June 2006 to October 2014, 646 patients met inclusion criteria. Biochemical profile was typical in 460 patients (71%), NC in 101 (16%), and NH in 85 (13%). IOPTH levels were higher at all time points in typical patients, p < 0.001. Surgical cure rates were significantly lower for NC patients (90.1%) than for typical (98.5%) or NH patients (97.7%), p < 0.001, although a stricter criteria for cure was used in this group (normal calcium AND normal PTH). In a multivariable linear mixed model, NC patients had a significantly slower rate of IOPTH decline (p < 0.001 at 10 min).

CONCLUSIONS

Here, we better characterize the atypical variants of pHPT. Using a stricter definition of cure in the NC variant, these patients have a lower surgical cure rate than typical or NH variants in pHPT. The IOPTH curve is affected by biochemical profile, with both NC and NH patients having lower absolute values and NC patients having a slower decline.

Normocalcaemic primary hyperparathyroidism: An update on diagnostic and management challenges

Normocalcaemic primary hyperparathyroidism is a condition that can present with intermittent hypercalcemia or may evolve into hypercalcemic primary hyperparathyroidism. This milder biochemical entity remains incompletely understood because of a lack of long-term health outcomes regarding both medical and surgical approaches to its management. Medical therapies have shown some efficacy. A limited number of studies have found that bisphosphonates increase bone mineral density, and calcimimetics may decrease the risk of nephrolithiasis in patients with normocalcaemic primary hyperparathyroidism. Studies have also described patient outcomes after applying the same surgical criteria used for patients with hypercalcaemic primary hyperparathyroidism to those with the normocalcaemic form of the disease. These studies suggest that parathyroid surgery appears to be effective in normalizing elevated serum parathyroid hormone concentrations and decreasing adverse renal and skeletal outcomes in patients with normocalcaemic hyperparathyroidism. Given the available data and overall lack of consensus regarding the optimal management of these patients, a reasonable approach is to tailor treatment to the individual patient by considering their risk factors for new or accelerated bone loss, kidney stones, diminished quality of life, and cardiovascular disease.

Normocalcemic Hyperparathyroidism: Study of its Prevalence and Natural History

CONTEXT

Normocalcemic hyperparathyroidism (NPHPT) is characterized by persistently normal calcium levels and elevated parathyroid hormone (PTH) values, after excluding other causes of secondary hyperparathyroidism. The prevalence of the disease varies greatly and the data on the natural history of this disease are sparse and inconclusive.

OBJECTIVES

The objectives of this study are to describe the prevalence of NPHPT and its natural history in a referral population and to compare the variability of serum calcium with a group of patients with primary hyperparathyroidism (PHPT).

DESIGN

A retrospective study was conducted over 5 years.

SETTING

The setting for this study was a metabolic bone referral center.

PATIENTS

A total of 6280 patients were referred for a bone mineral density measurement (BMD).

MAIN OUTCOME MEASURES

The prevalence and natural history of NPHPT and variability of calcium were the main outcome measures.

RESULTS

We identified NPHPT patients using data from the day of the BMD measurement. We excluded patients with low estimated glomerular filtration rate (eGFR) or vitamin D, or with no measurements available. Based on the evaluation of their medical files, we identified 11 patients with NPHPT (prevalence 0.18%). Only 4 patients had consistent normocalcemia throughout their follow-up, with only 2 also having consistently high PTH. None had consistently normal eGFR or vitamin D.Intermittent hypercalcemia was present in 7 of the 11 NPHPT patients. The mean adjusted calcium was found to be significantly lower in the NPHPT group compared with the PHPT group but higher than the control group. PTH was similar for NPHPT and PHPT. These 2 groups had similar variability in serum calcium.

CONCLUSIONS

NPHPT patients often have episodes of hypercalcemia. We believe that NPHPT is a mild form of PHPT.

Recent advances in the understanding and management of primary hyperparathyroidism

Primary hyperparathyroidism is a hormonal disorder whose prevalence is approximately 1–2% in the United States of America. The disease has become more recognizable to clinicians in an earlier phase and, at present, patients can be diagnosed with “classic”, “normocalcemic”, “normohormonal”, or “mild, asymptomatic” primary hyperparathyroidism. Surgery, with a focused parathyroidectomy when possible, or a four-gland exploration, is the only way to cure the disease. Cure is determined by use of intra-operative parathyroid hormone monitoring with long-term cure rates ranging from 90–95%. Newer adjuncts to surgery include CT or PET imaging and near-infrared immunofluorescence. This article highlights updates in parathyroid disease and advances in parathyroid surgery; it does not provide a comprehensive summary of the disease process or a review of surgical indications, which can be found in the AAES guidelines or NIH Symposium on primary hyperparathyroidism.

Intraoperative Parathyroid Hormone Monitoring in the Surgical Management of Sporadic Primary Hyperparathyroidism

Intraoperative parathyroid hormone monitoring (IPM) has been shown to be a useful adjunct during parathyroidectomy to ensure operative success at many specialized medical centers worldwide. Using the Miami or ">50% intraoperative PTH drop" criterion, IPM confirms the complete excision of all hyperfunctioning parathyroid tissue before the operation is finished, and helps guide the surgeon to identify additional hyperfunctioning parathyroid glands that may necessitate further extensive neck exploration when intraoperative parathyroid hormone (PTH) levels do not drop sufficiently. The intraoperative PTH assay is also used to differentiate parathyroid from non-parathyroid tissues during operations using fine needle aspiration samples and to lateralize the side of the neck harboring the hypersecreting parathyroid through differential jugular venous sampling when preoperative localization studies are negative or equivocal. The use of IPM underscores the recognition and understanding of sporadic primary hyperparathyroidism (SPHPT) as a disease of function rather than form, where the surgeon is better equipped to treat such patients with quantitative instead of qualitative information for durable long-term operative success. There has been a significant paradigm shift over the last 2 decades from conventional to focused parathyroidectomy guided by IPM. This approach has proven to be a safe and rapid operation requiring minimal dissection performed in an ambulatory setting for the treatment of SPHPT.

Comparative prospective study on the presentation of normocalcemic primary hyperparathyroidism. Is it more aggressive than the hypercalcemic form?

BACKGROUND

Some patients with primary hyperparathyroidism (PHPT) have an elevated PTH that does not always correlate with high blood calcium levels. We aimed to compare the clinical presentation between normocalcaemic and hypercalcaemic forms using ionized calcium levels as an inclusion criterion.

METHODS

We included all patients referred for surgery for PHPT between January 2015 and December 2017. Patients were divided into 2 groups (hypercalcaemic (hPHTP)/normocalcaemic (nPHPT)).

RESULTS

104 patients were included.64% of the patients who were initially classified as normocalcaemic had high ionized calcium levels. There were no differences between groups except in terms of bone resorption parameters:patients with hypercalcaemia had higher osteocalcin (37.4vs23.5 ng/mL,P = .02), collagen amino-terminal propeptide (73.5vs49.2 ng/mL,P = .005), and beta-CTX levels (0.68vs0.38 ng/mL,P = .001). Bone involvement as measured by densitometry was similar.

CONCLUSSIONS

When these patients' diagnosis and classification is accurate, their clinical presentation and symptoms are similar to those of the classical form. Since the only difference is in terms of bone resorption parameters, in most cases it seems to be an attenuated form or even similar to the classical presentation. The improvement in diagnostic sensitivity supports the use of ionized calcium levels in patients suspected to have nPHPT.

Normocalcemic hyperparathyroidism: A Collaborative Endocrine Surgery Quality Improvement Program analysis

BACKGROUND

Normocalcemic primary hyperparathyroidism may be more challenging to cure compared with classical primary hyperparathyroidism. The aim of this study was to utilize a multi-institutional database to better characterize this condition.

METHODS

The Collaborative Endocrine Surgery Quality Improvement Program database was queried for all patients who underwent parathyroidectomy for sporadic primary hyperparathyroidism. Patient characteristics, operative details, pathology, and outcomes data were compared between patients with normocalcemic primary hyperparathyroidism and those with hypercalcemia.

RESULTS

Among 7,569 patients, 9.7% (733) were normocalcemic primary hyperparathyroidism. Mean age at surgery and sex were similar for normocalcemic primary hyperparathyroidism and primary hyperparathyroidism with hypercalcemia. The primary hyperparathyroidism with hypercalcemia cohort had a single parathyroid resected more frequently than the normocalcemic primary hyperparathyroidism group (73.3%% vs 47.5%, P < .05). Patients with normocalcemic primary hyperparathyroidism had a higher rate of subtotal (3.5 gland) resection (10.0% vs 4.7%, P < .05). Pathology reported a higher frequency of multigland hyperplasia in the normocalcemic primary hyperparathyroidism cohort (43.1% vs 21.9%, P <.05). In the normocalcemic primary hyperparathyroidism cohort, 47 patients (6.4%) underwent remedial surgery compared with 307 patients (4.5%) with primary hyperparathyroidism with hypercalcemia (P < .05). The rate of clinical concern for persistent hyperparathyroidism was similar between the 2 groups (P = .09) but not reported in 25% overall.

CONCLUSION

Patients with normocalcemic primary hyperparathyroidism have higher rates of multigland disease and remedial surgery compared with primary hyperparathyroidism with hypercalcemia.

Mild sporadic primary hyperparathyroidism: high rate of multiglandular disease is associated with lower surgical cure rate

BACKGROUND

Mild primary hyperparathyroidism (serum calcium ≤ 2.85 mmol/L) is the most representative form of pHPT nowadays. The aim of this study was to evaluate its subtypes and the multiglandular disease (MGD) rate as it may lower the sensitivity of preoperative parathyroid scintigraphy and the surgical cure rate.

METHODS

We retrospectively included patients with mild pHPT who underwent parathyroid dual-tracer scintigraphy with ^99mTc-MIBI SPECT/CT and surgery between January 2013 and December 2015. Cure was defined as normalization of serum calcium (or PTH in the normocalcemic form) at 6 months. MGD was defined by either two abnormal resected glands or persistent disease after resection of at least one abnormal gland.

RESULTS

We included 121 patients. Median preoperative serum calcium was 2.68 mmol/L and median PTH was 83.4 pg/mL. A total of 141 glands were resected (95 adenomas, 33 hyperplasias). The subtypes were 57% classic, 32.2% normohormonal, and 10.7% normocalcemic. MGD occurred in 23.5% of patients divided as 13%, 30%, and 64% respectively (p = 0.0011). The surgical cure rate was 85.2%. The normocalcemic form had lower cure rate than the normohormonal (45% vs 84%, p = 0.018) and classic forms (45% vs 93%, p = 0.0006). MIBI scintigraphy identified at least one abnormal lesion, later confirmed by the pathologist in 90/98 patients, making the sensitivity per patient 91.8% (95% CI 84.1-96.2%).

CONCLUSIONS

MGD is strongly associated with mild pHPT, especially the normocalcemic form where it accounts for 64% of cases. Bilateral neck exploration should be performed in this population to improve the cure rate, even if the scintigraphy shows a single focus.

Management of normocalcemic primary hyperparathyroidism

Traditional hypercalcemic primary hyperparathyroidism is a common endocrine disease. Patients with a history of nephrolithiasis or a suspected metabolic bone disease are increasingly being identified with elevated PTH concentrations in the setting of consistently normal serum and ionized calcium concentrations. In the absence of secondary causes of hyperparathyroidism, a diagnosis of normocalcemic primary hyperparathyroidism is reasonable. As most cohorts described in the literature are from referral populations, involvement of the skeleton and the kidneys is common, two traditional target organs of primary hyperparathyroidism. Data from small cohorts show patients with normocalcemic disease respond similarly to hypercalcemic primary hyperparathyroidism with regard to medical and surgical approaches. In normocalcemic patients, multiglandular disease may be more common. In this article, we review the available literature on the epidemiology, diagnosis, clinical features, medical and surgical management of this newer phenotype of primary hyperparathyroidism.

Classic Primary Hyperparathyroidism Versus Normocalcemic and Normohormonal Variants: Do They Really Differ?

BACKGROUND

Normocalcemic (NCpHPT) and normohormonal (NHpHPT) variants have been recognized primary hyperparathyroidism entities that pose serious challenges. We sought to define the differences among them in a series of surgically treated patients.

PATIENTS AND METHODS

Between 2011 and 2015, 149 patients were enrolled into three groups: CpHPT (Ca > 10.2 mg/dL, PTH > 65 pg/mL), NCpHPT (normal Ca, PTH > 65 pg/mL) and NHpHPT (Ca > 10.2 mg/dL, normal PTH). Descriptive statistics and inter-group differences were computed, whereas multiple logistic/linear regression tests were used for further analysis.

RESULTS

Of these patients 125 were female and 24 male, mean age 56.3 years (range 8-83). A total of 115 (77.2%) patients presented with CpHPT, 23 (15.4%) with NCpHPT and 11 (7.4%) with NHpHPT. MGD was found in 25 (16.8%) patients and SGD in 124 (83.2%); multivariate analysis failed to reveal statistically significant association of MGD with any pHPT variant (CpHPT 16.5% vs NCpHPT 21.7% vs NHpHPT 9.1%, p = 0.726). Conversely, NCpHPT patients exhibited statistically significant smaller adenoma weight (p = 0.023). Moreover, U/S in these patients had smaller positive predictive value (p = 0.278), whereas concordance between U/S and MIBI was also lower (p = 0.669). The utility of MIBI and U/S differed significantly (p < 0.001); more frequent use of U/S was observed for all groups. However, their predictive values did not differ significantly (p = 0.832).

CONCLUSIONS

NCpHPT is more similar than different to CpHPT. NCpHPT constitutes the most challenging entity: it is associated with smaller adenoma weight, whereas U/S exhibited lower positive predictive value and lower concordance rate with MIBI. A trend for higher MGD presence in this group of patients was observed, though without statistical significance.

Minimally elevated preoperative parathyroid hormone level influences the management of primary hyperparathyroidism

OBJECTIVES/HYPOTHESIS

To determine the effect of preoperative parathyroid hormone (PTH) level on the extent of surgery and the accuracy of parathyroid imaging in primary hyperparathyroidism.

STUDY DESIGN

Retrospective cohort.

METHODS

Final diagnosis of single-gland adenoma and its location versus multigland disease was established in this retrospective cohort study. Positive predictive value, negative predictive value, and accuracy of imaging were analyzed in relation to preoperative PTH levels.

RESULTS

Eighty-seven percent of the 218 patients enrolled in the study underwent unilateral targeted operation and had a 97.9% (95% confidence interval: 95.8%-100%) success rate. However, in patients with PTH <65 pg/mL, 28.6% had bilateral exploration compared to 10.3% in those with PTH ≥65 pg/mL (P = .042). In patients with PTH <65 pg/mL, 7/21 (33.3%) had inaccurate sestamibi findings compared to 24/174 (13.8%) in patients with PTH ≥65 pg/mL (P = .047).

CONCLUSIONS

Accuracy of sestamibi drops significantly, by threefold, in patients with mild primary hyperparathyroidism and PTH <65 pg/mL. Patients with PTH < 65 pg/mL have a 2.5-fold higher rate of bilateral operation to identify the hypersecreting gland(s) compared to patients with PTH ≥65 pg/mL.

LEVEL OF EVIDENCE

4. Laryngoscope, 128:1016-1021, 2018.